Escapement mechanism



Jan. 8 1924.

cl H. BRIGDEN ESCAPEMENT MECHANISM Filed June' 8, 1922 $0 /7IljJllllllllll II Patented Jan. 8, 1924.

UNITED STATES CHARLES H. BRIGDEN, 0F WALTHAM, MASSACHUSETTS.

ESCAPEMENT MECHANISM.

Application filed June 8,

T 0 all whom it may concern-.-

Be it known that 1, CHARLES H. BRIGDEN, a citizen of the United States,residing at WValtham, in the county of Middlesex and State ofMassachusetts, have invented new and useful Improvements in EscapementMechanism, of which the following is a specification.

This invention relates to escapement mechanisms more particularlydesigned for tower clocks and primarily seeks to provide such amechanism which is unaffected by variations in the propelling force, orin the resistance encountered. Such variations are often caused inpractice by loads of snow and ice on the clock hands tending to retardthe movements of the hands to the left of the vertical median line ofthe clock and tending to accelerate their movement at the right of themedian line. It also provides a construction by which the usual heavycrutch is eliminated, so doing away with the friction of its bearings,substituting in place thereof a few simple comparatively light partssubstantially unsubject-ed to friction bearing.

For these and other purposes this invention provides a constructionwherein. the force for moving the pendulum, or other controlling member,is imparted thereto by a spring which is energized to a uniform amountfor each actuation of the pendulum regardless of variations in motor orresisting forces.

For a more complete understanding of this invention, together withfurther objects and advantageous details and combinations of parts,reference may be had to the accompanying drawings in which Figure 1 isan end elevation of the upper portion of a tower clock movementconstructed according to this invention, the pendulum being swung to oneside.

Figure 2 is a side elevation of the same portion of the mechanism.

Figure 3 is a perspective partly broken away of the spring clutch andpendulum suspension.

Figure 1 is a fragmentary view similar to a portion of Figure 1, butshowing the pendulum swung to the opposite side of the vertical.

Figure 5 is a diagrammatic view showing the principle of operation ofthis invention.

Referring to these drawings at 1 is shown an arbor carrying an escapewheel 2, this 1922. Serial No. 566,715.

arbor being journaled in a pair of side frames 3. This arbor isconnected through a pinion 4 and gear 5 with any suitable source ofmotive power not shown herein. Cooperating with the escape wheel 2 is apallet 6 fixed to a rock shaft 7. This rock shaft passes through anopening 8 in the forward frame member 3 and has reduced extremitieswhich are journaled in a pair of brackets 9 and 10 bolted or otherwisefixed to the under side of a top frame member 11.

The rock shaft 7 is journaled with capability of a slight endwise motionfor the purpose of providing against cramping of the shaft due to anywarping of the frames 3 or distortion due to temperature changes orother causes. The forward end of the rock shaft 7 has fixed thereto ablock member 14: which is forked at its outer end to form a pair of arms15. Depending between the pair of arms 15 is one of a pair of spacedarms 16 of a pendulum support 17. These arms 16 are slotted and withinthe slots are made fast the upper ends of a pair of leaf springs 18which form the pivotal axis of a pendulum, the upper member of whichcomprises a hanger 19 having spaced arms 20 positioned opposite the arms16 which are slotted to receive the lower ends of the springs 18 whichare made fast therein.

The member 19, as shown, is provided with a transverse pin 21 at itslower end over which the usual hook support of the pendulum rod (notshown) may be engaged. Between the arms 16 of the pendulum support so asto be straddled thereby and also fixed between the arms 15 of the blockor member 14 is the upper member 22 of a spring crutch. This crutchmember, as shown in Figures 3 and 5, is provided at its lower end with awide slot 23 and upwardly therefrom a narrower slot 24. Within thenarrower slot is fixed the upper end of a pendulum impulse leaf spring25 which is free to bend within the wide slot 23. The lower end of thisspring is fixed in the lower crutch block 26, the lower end of which isformed with a groove 27 slidably engaging a lug 28 mounted fortransverse adjustment by means of a screw 29 on the pendulum element 20.This construction insures against relative lateral movement of the block26 and the pendulum element 20, but permits axial movement of thepalletrock shaft 7, the block rocking with the pendulum.

The spring 25, which has been above re ferred to as the impulse spring,is designed to be flexed by rocking of the pallet shaft to impartswinging impulses to the pendulum, it as will later appear, alsodesigned to be flexed by movement of the pendulum to impart a furtherrocking motion to the pallet shaft to release the escape wheel.

In operation it is quite important that the center of oscillation of thepallet shaft, which is its axis should be directly in line *ith thepivotal center of the pendulum. F or this purpose adjustment of thesupport 17 has been provided both vertically and laterally. The verticaladjustment is provided by means of a set screw 30 threaded through theupper end of the support 17 and hearing at its low -r end on atransverse pin 31 which is seated in grooves in the upper face of theframe member 11 through a slot in which the member 1? depends. Lateraladjustment is effected by means of a pair of set screws 32 which passthrough opposite sides of the slotted portion of the frame member 11 andbear against opposite faces of the member 17. The end of the slot in themember 11 is normally closed by a cover plate 33. 7

ln order to impart rocking motion to the pallet shaft 7 to actuate thependulum the pallet; (S is provided with a pair of pallet teeth 40, eachtooth having an inclined face ll adapted to be engaged by the teeth ofthe escape wheel in such a manner as to wedge the corresponding tooth 40outwardly to impart a rocking movement to the pallet. In order toprevent the escape Wheel from riding past the teeth l one side of eachtooth is provided with a rest nib 42 against which the escape toothimpinges after it has ridden across the inclined face 41. This rest nibis at such an angle that there is no tendency for the escape tooth toswing the pallet; to disengage it therefrom.

The action of this mechanism will be understood by referring to Figures1, 4; and 5. in Figure 1 the pallet is shown as swung so that the righthand rest nib 4:2 is in engagement with a tooth of the escape wheel. lnthis position the pallet shaft has been rocked in the direction of thearrow 0 so that the upper end of the impulse spring is turned to theleft, thus flexing the spring in a direc tion to impart impulse to theright to the pendulum, the pendulum being shown in this figure as beingpositioned somewhat to the left of the center and in Figure at Y to itsextreme left hand position. In response to this flexing of the springthe pendulum starts to the right, permitting the impulse spring tostraighten. Its inertia carries it beyond the straight line position andimparts a slight bend in the opposite direction to the impulse spring atthe dotted line position 3/ of Figure 5. This bend in the oppositedirection reacts on the pallet shaft '7 to rock the pallet shaftslightly further in the direction of the arrow a, whereupon the righthand rest nib 42 is dislodged from the end of t 1e escape tooth whichimmediately slips by and a tooth on the opposite side engages theinclined face d1 of the left hand pallet tooth. This wedges the palletin the opposite direo tion to rock the pallet shaft in the direction ofthe arrow 7) in Figure 1 until the escape tooth is stopped by the lefthand rest nib 4:2. This position of the parts shows much exaggerated byfull lines in Figure 5. The impulse spring is therefore flexed in adirection to impart a left hand swing to the pendulum as this swing willstraighten the impulse spring, and it remains in this position while theinertia of the pendulum is being overcome and while the pendulum isstarted on its reverse motion. The extreme position of the pendulum tothe right hand side is shown in full lines in Figure 5 at X. Thependulum then swings to the left sufliciently to straighten the impulsespring, its inertia carries it still further to the left to the dottedline position a; and imparts a re verse fleXure to the impulse spring,rocking the pallet shaft still further in the direction of the arrow 5sufficiently to release the left hand rest nib 42 from the escape wheeltooth. and permitting the escape wheel to move on until a tooth engagesthe right hand inclined face 41 whereupon the cycle of operations isrepeated.

It will be seen from this description that the force applied to swingthe pendulum is imparted by a flexing of the impulse spring 25, which isalways flexed to the same amount regardless of the force applied to theescape wheel or to any resistance to the movement of the train ofmechanism operated thereby. For this reason the force applied to thependulum is constant and therefore its amplitude is constant. It is alsoseen that the usual heavy crutch with bearings is eliminated and lightparts with little friction substituted therefor.

While the pivotal center of the pendulum is shown as consisting of aleaf spring 18, it is evident that any other suitable type of pivotalmounting found desirable might be employed and it is also evident th atif desired other types of control than the pendulum might be employedwithout departing from the spirit or scope of the invention, though themechanism as shown is of a type which has been found quite satisfactoryin practice and it is the usual practice to employ pendulums in clocksof this character.

Having thus described an embodiment of this invention it should beevident that many other changes and modifications might be made thereinwithout departing from its spirit or scope as defined by the appendedclaims I claim:

1. In a mechanism of the class described, an escape wheel, a palletshaft, a pallet carried by said shaft and cooperating with said wheel, amember having a pair of spaced arms at its outer end made fast to oneend of said shaft, a block fixed between said arms adjacent their outerends, a support having spaced. arms straddling said block between thearms of said member, a pendulum, leaf springs forming the pivotal axisof said pendulum made fast to the arms of said support, and a leafspring fixed at one end in said block and having its opposite end inoperative engagement with said pendulum and through which swingingimpulses are imparted to said pendulum from said shaft.

2. In a mechanism of the class described, an escape wheel, a palletshaft, a pallet carried by said shaft and cooperating with said wheel, amember having a pair of spaced arms at its outer end made fast to oneend of said shaft, a block fixed between said arms adjacent their outerends, a support having spaced arms straddling said block between thearms of said member, a pendulum, leaf springs forming the pivotal axisof said pendulum made fast to the arms of said support, a leaf springfixed at one end to said block and having its opposite end in operativeengagement with said pendulum and through which the swinging impulsesare imparted to said pendulum from said shaft, and means to adjust saidsupport to bring the pivotal center of said pendulum in the axis of saidshaft.

3. In a mechanism of the class described, a spring crutch comprising anupper block having a slot in its lower end, a leaf spring fixed in saidblock above said slot and extending through said slot out of contactwith the side walls thereof, a lower block to the upper end of whichsaid lower end of said spring is made fast, and means on said lowerblock constructed to engage a pendulum to impart swinging motion theretowhile permitting relative motion perpendicular to the plane of swing.

4. In a mechanism of the class described, a pallet shaft, a support, apendulum pivoted to said support, a spring fixed at one end to saidshaft, a block to which the opposite end of said spring is fixed, andinterengaging elements on said pendulum and block through which saidswinging impulses may be imparted between said shaft and pendulum butwhich permit a limited endwise movement of said shaft relative to saidsuport. p In testimony whereof I have afiixed my signature.

CHARLES H. BRIGDEN.

